JP2016042681A - Radio communication system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system for a vehicle, which is lower in cost and is arranged so that the frequency of a wireless communication part can be controlled.SOLUTION: A radio communication system for a vehicle comprises: an on-vehicle device installed in the vehicle; and a portable device that a user carries. The on-vehicle device executes a predetermined function based on a radio signal transmitted from the portable device. The on-vehicle device has: an acquisition part for acquiring reference frequency information including a reference frequency on which frequency control is based; an on-vehicle device transmit part for transmitting the reference frequency information; and an on-vehicle device receiving part for receiving a radio signal from the portable device. The portable device includes: a first portable device receiving part for receiving the reference frequency information; and a transmission frequency control part for controlling, based on the received reference frequency information, a transmission frequency of a portable device transmit part for transmitting a radio signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle radio communication system.

  A smart entry system, which is one of the wireless communication systems for vehicles that realize various functions in a vehicle by wireless communication between a portable device owned by a user and an in-vehicle device mounted on the vehicle, has a mechanical key. Even if it is not used, authentication can be performed by wireless communication between the portable device and the in-vehicle device, and the operation desired by the user such as door unlocking and engine starting can be performed based on the authentication result.

  A control method for correcting a communication frequency shift between transmission and reception has been devised in a system that performs wireless communication such as a radio clock or a mobile phone. For example, when the slave station makes a frequency correction request to the master station as necessary, the master station provides frequency correction information for correcting a deviation between the reference communication frequency and the slave station communication frequency based on the request. Create and transmit, and the slave station corrects the communication frequency based on the frequency correction information (see Patent Document 1).

  In addition, a radio-controlled timepiece that adjusts the frequency of the local oscillation signal generated by the local oscillation unit based on the frequency of the local oscillation signal according to the standard radio wave so that the center frequency and the intermediate frequency of the crystal filter coincide with each other. It has been devised (see Patent Document 2).

JP 2009-100406 A JP 2013-178151 A

  In the prior art, the receiving unit uses AFC (Automatic Frequency Control) that adjusts the frequency using RSSI (Received Signal Strength) so as to match the transmission frequency from the transmitting unit having an accurate frequency source, When necessary, the transmitter transmits a reference signal for frequency correction to the transmitter, and the transmitter generates correction information based on the difference from its own frequency and feeds it back to the receiver to adjust the frequency.

  This is based on the premise that the transmitting unit has an accurate frequency, so that the receiving unit can use an inexpensive oscillator, but the transmitting unit requires a precise oscillator and can reduce costs. There wasn't.

  In view of the above problems, an object of the present invention is to provide a vehicular radio communication system capable of adjusting the frequency of a radio communication unit at a lower cost.

  A vehicle wireless communication system for solving the above-described problem includes an in-vehicle device mounted on a vehicle and a portable device possessed by a user. The in-vehicle device is predetermined based on a wireless signal transmitted from the portable device. A vehicle wireless communication system that performs the above function, wherein the in-vehicle device acquires reference frequency information including a reference frequency that is a basis for adjusting the frequency, and in-vehicle device transmission that transmits the reference frequency information And a vehicle-mounted device receiving unit that receives a radio signal from the portable device, and the portable device receives a wireless signal based on the first portable device receiving unit that receives the reference frequency information and the received reference frequency information. A transmission frequency adjusting unit that adjusts the transmission frequency of the portable device transmitting unit that transmits the signal.

  With the above configuration, an inexpensive oscillator with low accuracy can be used on the portable device side of the vehicle wireless communication system, and the cost can be reduced. In addition, since the transmission / reception frequency can be matched with the in-vehicle device, the reception bandwidth on the reception side can be narrowed, and the effect of improving the reception sensitivity and the resistance to ambient noise is achieved.

The figure which shows the structure of the radio | wireless communications system for vehicles. The figure which shows another example of a structure of the radio | wireless communications system for vehicles. The flowchart which shows the frequency adjustment process of a portable device. The flowchart which shows the frequency adjustment process of a vehicle-mounted apparatus.

  As shown in FIG. 1, the vehicular wireless communication system 100 includes an in-vehicle device 1 mounted in a vehicle 101 (for example, a vehicle interior) and a portable device 2 possessed by a user.

  The in-vehicle device 1 includes an ECU 10, an RF reception unit 20 (an in-vehicle device reception unit according to the present invention), an LF transmission unit 30 (an in-vehicle device transmission unit according to the present invention), and the like connected to the ECU 10.

  The ECU 10 (acquisition unit of the present invention) is connected to the control unit 11 and the control unit 11 and, for example, an IF (signal input / output) unit for performing data communication with other vehicle devices via the in-vehicle LAN 15 12, the control unit 11 includes an oscillator 13 which generates a clock signal for operating, which is a crystal oscillator or a ceramic oscillator.

  The control unit 11 is configured as a computer including a well-known CPU, a peripheral circuit, and a memory (all not shown). The memory stores the in-vehicle device control program. The CPU executes the in-vehicle device control program, thereby realizing various functions of the in-vehicle device 1.

  The RF receiver 20 receives a radio signal (for example, a response signal) transmitted from the portable device 2 using, for example, an RF (high frequency) band radio wave. The RF receiving unit 20 includes a control unit 21 (reception frequency adjusting unit and comparison unit of the present invention) that controls the operation of the entire RF receiving unit 20, and an IF unit for exchanging data with the outside of the RF receiving unit 20. 22, an oscillator 23 that is a crystal oscillator or a ceramic oscillator that generates a clock signal for operating the RF receiver 20, and a memory 24 that stores data necessary for the operation of the RF receiver 20.

  The RF receiver 20 includes a frequency divider that divides the clock signal from the oscillator 23 and a setting unit 25 (reception frequency adjusting unit of the present invention) including a register that sets a frequency division ratio of the frequency divider. A PLL (Phase Locked Loop) circuit 26 (reception frequency adjusting unit of the present invention) that generates and outputs a reference signal having a predetermined frequency (referred to as a reference frequency) based on an output signal from the frequency divider, and an output from the PLL circuit 26 A frequency counter 27 (reception frequency adjusting unit of the present invention) that counts the frequency of the received reference signal, for example, a mixer that mixes the reference signal output from the PLL circuit 26 and the received wave, and an intermediate frequency amplifier. In addition, a detection unit 28 that extracts (demodulates) the original signal from the modulated reception wave, and a filter 29 that extracts only a signal having a desired frequency from the reception wave and outputs the signal to the detection unit 28 are included.

  The LF transmission unit 30 transmits a radio signal (for example, a request signal) to the portable device 2 using, for example, an LF (long wave) band radio wave. The antenna is provided, for example, in a door handle, an indoor antenna in the vehicle interior, inside the trunk, and outside the trunk lid (all not shown), respectively, in the vicinity outside the corresponding door, in the vehicle interior, inside the trunk, and outside the trunk. Only within a limited transmission area (for example, a range of 1 to 1.5 m from the antenna).

  The portable device 2 includes an RF transmitter 60 (a portable device transmitter of the present invention) and an LF receiver 70 (a first portable device receiver of the present invention). In addition to these, a control unit (not shown) that controls the overall operation of the portable device 2 is provided. The configuration of this control unit is the same as that of the control unit 11 of the ECU 10.

  The RF transmission unit 60 transmits a radio signal to the in-vehicle device 1 using a UHF band radio wave. The RF transmission unit 60 includes a control unit 61 (transmission frequency adjusting unit and comparison unit of the present invention) that controls the overall operation of the RF transmission unit 60, and a ceramic oscillator that generates a clock signal for operating the RF transmission unit 60. And a memory 64 for storing data necessary for the operation of the RF transmitter 60.

  The RF transmitter 60 also includes a setting unit 65 (transmission frequency adjusting unit of the present invention) including a frequency divider that divides the clock signal from the oscillator 63 and a register that sets a frequency division ratio of the frequency divider, a clock. A PLL circuit 66 (transmission frequency adjusting unit of the present invention) that generates and outputs a reference signal serving as a reference of the transmission frequency to the transmission unit 68 based on the signal and the frequency division ratio, and the frequency of the reference signal output from the PLL circuit 66 A frequency counter 67 (transmission frequency adjusting unit of the present invention) for counting (referred to as a reference frequency), a mixer for mixing the reference signal output from the PLL circuit 66 and the transmission wave, a known modulation circuit, an amplifier, etc. A transmission unit 68.

  The LF reception unit 70 includes a detection unit 71 that extracts an original signal from the modulated wave, and receives a radio signal transmitted from the in-vehicle device 1 using an LF band radio wave.

  The in-vehicle device 1 and the portable device 2 constitute a known smart entry system. That is, a request signal is transmitted from the in-vehicle device 1 to the portable device 2 via the LF transmission unit 30. The portable device 2 that has received the request signal via the LF receiver 70 transmits a response signal including an ID code for identifying itself to the in-vehicle device 1 via the RF transmitter 60. The control unit 11 of the ECU 10 collates the ID code received via the RF receiving unit 20 with a master code stored in advance in a memory (not shown) included in the ECU 10, and when both match (normal verification) ), A control command including permission to lock or unlock the door or permission to start the engine is output to the corresponding device.

  The ECU 10 can perform data communication with another vehicle device via the IF unit 12 via the in-vehicle LAN 15. Examples of the vehicle device include a known meter device 40 that displays vehicle speed, engine speed, cooling water temperature, fuel remaining amount, date and time, and the like. The meter device 40 includes a clock function unit 41, an IF 42, and a crystal oscillator 43 that generates a clock signal for operating the meter device 40. Since the timepiece function unit 41 requires accuracy, a crystal oscillator (accuracy: about 1.0E-9) is used (accuracy of the ceramic oscillator: about 0.5%).

The reference frequency information acquisition method of the ECU 10 in the configuration of FIG. 1 will be described.
(Acquisition method: Part 1)
The reference frequency information output from the meter device 40 is acquired via the in-vehicle LAN 15 at a predetermined timing. The reference frequency information includes at least one of the following.
The current value of the frequency of the crystal oscillator 43 (measured by the meter device 40).
-H level time and L level time of the pulsed clock signal. The ECU 10 calculates the current value of the frequency from these.
The current state (H level or L level) of the pulsed clock signal. The ECU 10 samples this state, measures the H level time and the L level time of the clock signal, and calculates the current value of the frequency.
The rated value of the crystal oscillator 43 may be included in the reference frequency information.

  The above-described configuration is “the acquisition unit acquires reference frequency information from a vehicle device mounted on the vehicle”. With this configuration, even when a highly accurate oscillator is not used in the vehicle wireless communication system (that is, the in-vehicle device), the frequency adjustment of the portable device transmission unit can be performed, and the communication accuracy can be improved.

(Acquisition method: 2)
When a crystal oscillator is used for the oscillator 23 of the RF receiver 20 of the ECU 10, reference frequency information is acquired via the IF unit 22. The reference frequency information is the same as described above. Moreover, you may use the above-mentioned standard frequency as a reference frequency.

  The above-described configuration is “the acquisition unit acquires reference frequency information from the in-vehicle device reception unit”. With this configuration, when a highly accurate oscillator is used in an in-vehicle device, it is not necessary to acquire reference frequency information from the vehicle device, and the frequency of the portable device transmitter can be adjusted within the vehicle wireless communication system It becomes.

  When the ECU 10 acquires the H level time and the L level time of the clock signal or the current state of the clock signal, the ECU 10 converts the frequency into a frequency, and includes the frequency value as the acquired reference frequency information, for example, in the request signal. Then, the data is transmitted to the portable device 2 via the LF transmitter 30.

  The configuration of the RF receiving unit 20 and the RF transmitting unit 60 described above is “the transmission frequency adjusting unit of the portable device transmitting unit and the receiving frequency adjusting unit of the in-vehicle device receiving unit each divide the clock signal generated by the oscillator. A frequency divider, a PLL circuit that generates a reference signal having a predetermined frequency from the divided clock signal, a frequency counter that counts the frequency (reference frequency) of the reference signal, and a reference that counts the reference frequency A comparison unit that compares the frequency of the signal, and a setting unit that calculates a new division ratio based on the comparison result and sets the division ratio in the divider, and adjusts the frequency of the reference signal By doing so, the transmission frequency of the portable device transmission unit and the reception frequency of the in-vehicle device reception unit are adjusted. " With this configuration, it is possible to adjust the frequency of the portable device transmitter and the in-vehicle device receiver by adjusting the reference frequency with a configuration using a PLL circuit or the like for the portable device transmitter and the in-vehicle device receiver. It can be improved.

  FIG. 2 shows another example of the vehicle radio communication system 100. The configuration in FIG. 2 is a modification of FIG. 1, and thus the same reference numerals are given to the same configurations as in FIG. 1, and detailed descriptions thereof are omitted here. The vehicle wireless communication system 100 includes an in-vehicle device 1 mounted on a vehicle 101, a portable device 2 and a portable terminal 3 possessed by a user.

  The in-vehicle device 1 includes a DCM (Data Communication Module) that is connected to the ECU 10 and communicates with a facility outside the vehicle such as the base station 102 via a public communication line in addition to the configuration of FIG.

  The portable device 2 includes a short-range wireless communication unit 80 (second portable device receiver of the present invention) in addition to the configuration of FIG. The short-range wireless communication unit 80 receives data transmitted from the mobile terminal 3 using a short-range wireless communication technology such as BLUETOOTH (registered trademark), for example. In particular, BLUETOOTH can communicate only between devices that have been paired in advance, so that a third party cannot intercept the communication content, and security can be ensured.

  The portable terminal 3 uses, for example, a tablet-type terminal represented by a well-known smartphone (a general term for a portable information terminal that is equipped with a touch panel on a display portion such as a liquid crystal display and is operated with a finger). The mobile terminal 3 has a function similar to that of the short-range wireless communication unit 80 of the portable device 2 in addition to the functions normally provided in the tablet terminal, and the short-range wireless communication unit 90 (the mobile terminal reception unit and the mobile terminal transmission unit of the present invention). ), And a communication unit 91 for communicating with the base station 102.

  In the configuration of FIG. 2, the ECU 10 transmits the acquired reference frequency information (the acquisition method is the same as described above) to the mobile terminal 3 via the DCM 50 to the base station 102. When the portable terminal 3 receives the reference frequency information via the communication unit 91, the portable terminal 3 transfers the reference frequency information to the portable device 2 via the short-range wireless communication unit 90.

  The configuration of FIG. 2 includes “a portable terminal held by a user, and the portable terminal includes a portable terminal receiving unit that receives reference frequency information and a portable terminal transmission unit that transmits reference frequency information. , Including a second portable receiver unit that receives reference frequency information from the portable terminal ”. With this configuration, even if the portable device is outside the communication range of the in-vehicle device, if the user has a portable terminal, the public device can be used to refer to the portable device from the in-vehicle device via the portable terminal. Frequency information can be transmitted. Therefore, it is possible to periodically adjust the frequency regardless of the position of the portable device.

  In the configuration of FIG. 2, the LF transmission unit 30 of the in-vehicle device 1 and the LF reception unit 70 of the portable device 2 as illustrated in FIG. 1 may not be included. That is, the configuration of FIG. 2 is not only a smart entry system but also a well-known keyless entry system (an in-vehicle device that receives a wireless signal from a portable device controls locking / unlocking of a vehicle door), a remote engine Like the start system (the vehicle-mounted device that receives the wireless signal from the portable device controls the start of the engine of the vehicle), the vehicle-mounted device performs a predetermined function based on the wireless signal transmitted from the portable device. However, even in a configuration in which a radio signal cannot be directly transmitted from the in-vehicle device to the portable device, the frequency adjustment of the portable device transmission unit can be performed.

  The frequency adjustment process executed by the control unit 61 of the RF transmission unit 60 of the portable device 2 in FIG. 3 will be described. First, it is determined whether or not a radio signal is received from the in-vehicle device 1 (in the configuration of FIG. 1) or the portable terminal 3 (in the configuration of FIG. 2). When a radio signal is received (S11: Yes), it is checked whether or not reference frequency information is included in the radio wave. When the reference frequency information is not included (S12: No), this process is ended, or another process corresponding to the content of the radio signal is executed.

  On the other hand, when the reference frequency information is included (S12: Yes), the reference frequency information is acquired (for example, temporarily stored in the memory 64) (S13). Next, the count value of the reference frequency counted by the frequency counter 67 is compared with the reference frequency (S14). As a result of the comparison, when the difference between the two is within a predetermined standard (S15: Yes), this processing is terminated.

If the rated value of the reference frequency and the rated value of the reference frequency are different,
(New reference frequency) = (Reference frequency) x (Rated value of standard frequency) / (Rated value of reference frequency)
Use to compare.

On the other hand, when the difference between the two is not within the predetermined reference (S15: No), the correction value of the reference frequency is calculated using at least one of the following (S16).
The relationship between the difference between the two and the correction value (for example, the frequency division ratio) is stored in advance in the memory 64 as map data, and the map is complemented to calculate the correction value.
A correction value is calculated by substituting the difference between the two into a predetermined calculation formula.

  Next, the calculated correction value is set in the register of the setting unit 65, and the reference frequency is corrected (S17). Thereafter, the process shifts to a response signal transmission waiting state. This improves the accuracy of the frequency of the response signal to be transmitted next time.

  The frequency adjustment process performed by the control unit 21 of the RF receiving unit 20 of the in-vehicle device 1 in FIG. 4 will be described. This is executed when a ceramic oscillator with relatively low accuracy is used for the oscillator 23. This configuration is “the acquisition unit acquires reference frequency information from a vehicle device mounted on the vehicle”. With this configuration, even when a highly accurate oscillator is not used in the vehicular wireless communication system (on-vehicle device, portable device), the frequency adjustment of the portable device transmission unit can be performed, and the communication accuracy can be improved.

First, it is determined whether or not a predetermined adjustment timing has arrived. The adjustment timing uses at least one of the following.
The timing for transmitting the request signal from the LF transmitter 30 is set as the adjustment timing (in the case of the smart entry system).
The above-described configuration is as follows: “The in-vehicle device transmits a request signal from the in-vehicle device transmitter, and the portable device responds to the request signal received by the first portable device receiver, and includes a response ID that identifies the portable device. The vehicle-mounted device transmits a signal, and the vehicle-mounted device receives the ID of the response signal received by the vehicle-mounted device receiving unit and a collation unit that collates a master ID stored in advance, and a predetermined vehicle And a control unit that controls the operation of the function, and transmits the reference frequency information when transmitting the response signal ”. With this configuration, the adjustment timing can be set so as not to hinder the operation of the smart entry system.

・ When frequency adjustment is performed at a predetermined cycle, the cycle is set as the adjustment timing.

  When the adjustment timing has arrived (S31: Yes), the ECU 11 is requested for reference frequency information. As described above, the ECU 11 acquires reference frequency information from the meter device 40 and outputs it to the RF receiver 20. The control unit 21 acquires this reference frequency information (for example, temporarily stores it in the memory 24) (S32).

  Next, the measured value of the standard frequency counted by the frequency counter 27 is compared with the reference frequency (S33). As a result of the comparison, when the difference between the two is within a predetermined standard (S34: Yes), this process is terminated.

  On the other hand, when the difference between the two is not within the predetermined reference (S34: No), the correction value of the reference frequency is calculated in the same manner as in step S16 of FIG. 3 (S35). Next, the calculated correction value is set in the register of the setting unit 25, and the reference frequency is corrected (S36). Thereafter, the process shifts to a reception waiting state for a response signal from the portable device 2. Thereby, the reception accuracy of the response signal from the next time is improved.

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

DESCRIPTION OF SYMBOLS 1 In-vehicle apparatus 2 Portable machine 3 Portable terminal 10 ECU (acquisition part)
20 RF receiver (in-vehicle device receiver)
21 Control unit (reception frequency adjustment unit, comparison unit)
23 Oscillator 25 Setting section (including frequency divider, receiving frequency adjustment section)
26 PLL circuit 27 Frequency counter (reception frequency adjustment unit)
30 LF transmitter (in-vehicle device transmitter)
40 Meter device (vehicle device)
60 RF transmitter (portable device transmitter)
61 Control unit (transmission frequency adjustment unit, comparison unit)
63 Oscillator 65 Setting section (including frequency divider, transmission frequency adjustment section)
66 PLL circuit 67 Frequency counter (transmission frequency adjustment unit)
70 LF receiver (first portable receiver)
80 Short-range wireless communication unit (second mobile device receiver)
90 Short-range wireless communication unit (mobile terminal receiver, mobile terminal transmitter)

Claims (7)

Including an in-vehicle device mounted on a vehicle and a portable device possessed by a user,
A vehicle wireless communication system in which the in-vehicle device performs a predetermined function based on a wireless signal transmitted from the portable device,
The in-vehicle device is
An acquisition unit for acquiring reference frequency information including a reference frequency serving as a basis for adjusting the frequency;
An in-vehicle device transmitter for transmitting the reference frequency information;
An in-vehicle device receiver that receives a radio signal from the portable device;
With
The portable device is
A first portable receiver that receives the reference frequency information;
Based on the received reference frequency information, a transmission frequency adjustment unit that adjusts a transmission frequency of a portable device transmission unit that transmits the wireless signal;
A vehicular wireless communication system. Including a portable terminal possessed by the user,
The portable terminal is
A portable terminal receiver for receiving the reference frequency information;
A portable terminal transmitter for transmitting the reference frequency information;
With
The portable device is
The vehicular wireless communication system according to claim 1, further comprising a second portable device receiver that receives the reference frequency information from the portable terminal.   The vehicular wireless communication system according to claim 2, wherein the portable terminal is a tablet terminal.   The said acquisition part is a radio | wireless communications system for vehicles of any one of Claim 1 thru | or 3 which acquires the said reference frequency information from the apparatus for vehicles mounted in the said vehicle.   The vehicular wireless communication system according to any one of claims 1 to 4, wherein the acquisition unit acquires the reference frequency information from the in-vehicle device reception unit. The in-vehicle device is
The vehicle wireless communication system according to claim 4, further comprising a reception frequency adjusting unit that adjusts a reception frequency of the in-vehicle device reception unit based on reference frequency information acquired from the vehicle device. The transmission frequency adjustment unit of the portable device transmission unit, the reception frequency adjustment unit of the in-vehicle device reception unit, respectively,
A frequency divider for dividing the clock signal generated by the oscillator;
A PLL circuit that generates a reference signal having a predetermined frequency from the divided clock signal;
A frequency counter for counting the frequency of the reference signal;
A comparison unit for comparing the reference frequency with the frequency of the counted reference signal;
Based on the result of the comparison, a new dividing ratio is calculated, and a setting unit that sets the dividing ratio in the divider;
Including
The vehicular wireless communication according to any one of claims 1 to 6, wherein a frequency of the reference signal is adjusted to adjust a transmission frequency of the portable device transmission unit and a reception frequency of the in-vehicle device reception unit. system.

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